I really do think that the adiaphora issue, when paired together with solas is the Achilles' heel of Lutheranism.
Lutherans have no legislative power and it is our undoing.
In this interpretation of the Confessions, Lutheranism is almost Quakerism in allowing freedom of conscience.
We should always distinguish three things: 1) What the Confessors wrote; 2) What the situation actually was among the Lutherans at the time; 3) What our interpretation is now, as colored by our sitz-im-leben (place in life/history).
For true Lutheranism, one needs to forget every modern incarnation of groups calling themselves "Lutheran" or "Synod" or "Church" and weigh the claims of the Confessors against themselves, against the Christian West and Christian East, and against history.
Each Lutheran Confession is "a" confession of what some "believed, taught, and practiced." Insofar as people calling themselves Lutheran today, we do not practice as much, teach as clearly or, believe as strongly.